Introduction

The Leptospira organisms can survive in the environment is an important factor in the epidemiology transmission and spread of the disease (Faine, 1982; Thierman, 1984). Waterholes or streams shared by game and cattle could be a source of Leptospira organisms (Faine, 1982). Leptospirosis has now been identified as one of the emerging infectious diseases due to the occurrence of large number of outbreaks. This disease is affecting humans, wild and as well as domestic animals. The disease has its significance in countries like India, because of large livestock, rodent and wildlife population, poor sanitary conditions and managemental practices, hot and humid climate and close, association between man and animals, providing a congenial environment for the spread of the disease. It is a complex disease caused by any of more than 220 known serovars, each of which can independently infect any possible host species. These pathogenic leptospires can colonize the kidneys and are shed in the urine for prolonged periods. Asymptomatic animals are the frequent source of infection to other animals and humans and are often difficult to identify.

Bovine leptospirosis is a cause of mastitis, abortion, stillbirth, or birth of weak calves. Leptospirosis is a well known cause of reproductive losses in cattle with relatively mild acute clinical signs. Abortion, stillbirth, or birth of weak calf occurs as a result of Leptospira infection. Abortion may occur several weeks after infection of the dam and is usually not associated with any obvious illness in the cow (Bahari et al., 2011). Leptospirosis has major economic concern when it is involved in the reproductive failure of food animals (Bomfim and Koury, 2006; Saglam et al., 2008). Infection of the reproductive system could result in a “storm of abortions” causing considerable economic losses from meat and milk reductions (Tooloei et al., 2008). However, underestimation of the actual situation of this disease in buffaloes due to limited information may conceal a considerable threat to public health and the economy of the buffalo industry. Hence, this study focused on elucidating the seroprevalence of leptospira infection in buffalo and the persistence of pathogenic leptospira in intensive farm settings.

Materials and Methods

An organized buffalo farm near Thanjavur district of Tamilnadu has reports of sporadic abortion and reduced milk yield. Among 150 Murrah buffaloes maintained, 15% of the animals showed above said symptoms. No vaccination program against leptospirosis has been applied in this farm. The buffaloes were in different stages of lactation and pregnancy. On thorough clinical investigation of the animals, suspected to be infected with leptospirosis were isolated. From 10 suspected animals for Leptospira infections approximately 10 ml of blood samples were collected from jugular vein of each cow by using disposable sterile syringe (10 ml) after using antiseptic from the cattle. The samples were allowed to clot and centrifuged for 1800 × g for 10 minutes. Then sera were separated and stored in 1.5 ml Eppendorf tube at -20°C until laboratory tests were performed. Screening test for Brucellosis was performed by using Rose Bengal plate agglutination test. The samples were sent to Zoonoses Research Laboratory, Center for Animal Health Studies, MMC, Chennai for serological confirmation. The collected serum samples were subjected to the microscopic agglutination test (MAT), which is the most commonly used technique for diagnosing leptospirosis in animals. Quantitative assay was carried out in ‘U’ bottom microtitration plates against the reacting serovars of leptospires. A drop (5 μl) of mixture from all final dilutions (1 in 50, 1 in 100, 1 in 200, 1 in 400, 1 in 800, 1 in 1600, 1 in 3200, 1 in 6400 and 1 in 12800) was prepared and the results were recorded under dark field microscopy. A titre of 1 in 100 and above is considered as positive in this study. All the suspected and in contact animals were treated with long acting oxytetracycline @20mg/ Kg by I/M route.

Results and Discussion

In the present study buffaloes from organized farm near Thanjavur district of Tamil Nadu in India were screened against leptospira antigens namely Icterohaemorrhagiae, Canicola, Grippotyphosa, Hebdomalis, Pomana, Autumalis, Pyrogens, Tarassovi, Ballus, Javanica, Australis and Hardjo. Reacting serovars presented in different animals were Ballum, Hardjo, Hebdomadis, Javanica and icterohaemorrhagiae. The results of serum samples of six buffalo’s revealed involvement of multiple agglutinins to the antigens of various serovars in the same animals. Presence of agglutinins to multiple serovars in the same animal was also reported by many workers (Chung, 1968; Carlos et al., 1971).The total positive animal were 6 (60.00%) out of 10 animals tested. All the animals were positive for L. hardjo in the present study, whereas Ramani Pushpa and Punya Kumari (2005) found L. pyrogens as predominant serovars in buffaloes. One animal was positive for three serogroups of Leptospira. One animal was positive for two serogroups of Leptospira and two animals were positive for one serogroup of Leptospira. L. ballum and L. Hebdomadis was found to be predominant serovars (found in four animals out of six). Of the sera sampled, L.ballum and L. hardjo showed agglutinating antibody titre of 1:1600 (Table 1). The animal was also suspected to be infected with sub clinical leptospirosis based on sero positivity in two animals without visible symptoms. Seroprevalence of subclinical leptospirosis in apparently healthy buffaloes in an organized farm was reported by Mrunalini and Ramasastry (2000).

Table 1: Distribution of serovar specific anti leptospiral antibodies and their titration in seropositive buffalo

The reported results of seroprevalence of leptospiral infection in cow are different from country to country. But this study was done with only 10 samples. However such high seropositivity has been recorded earlier by Natarajaseenivasan (1997) and Selvaraj et al. (2005), who reported 85.70 percent and 82.67 percent seropositivity, respectively.

On the other hand, in some countries lower prevalence has been recorded .This variation might be due to different geographical locations, management and husbandry practices, disease resistance among different breeds and levels of natural immunity. The majority of leptospira infections are asymptomatic and the presence of antibodies in the absence of infection indicates exposure to the organism in these animals which were approved by Hassanpour et al. (2011). Leptospirosis are particularly common in tropical and subtropical regions where environmental conditions favour the survival and transmission of Leptospira and also distinct variations in maintenance hosts and the serovars occur throughout the world (Hartskeerl, 2006). The apparent geographical variation in the sero-prevalence may reflect differences in the levels of natural immunity, management and husbandry practices employed, and sensitivities and specificities of the diagnostic methods used among researchers as well as genetic variation in disease resistance among the breeds (Swai and Schoonman, 2010). Cattle are the common hosts of leptospira interrogans serovar Hardjo observed by Ellis et al. (2000). A variety of clinical specimens may be used for isolation of leptospira from blood or cerebrospinal fluid, or urine sample may be used during the first 7-10 days of infection during symptomatic illness as reported by Bharti et al. (2003).

There was no previous observational study of the frequency of leptospirosis in buffaloes of farm has been attempted. The results of this investigation indicate the importance of leptospirosis as a possible cause of bovine abortion in dairy farms of Thanjavur district of Tamilnadu. The animals treated with long acting oxytetracyclins @ 20 mg/Kg by I/M route which made animals recover without any further symptoms. No paired sera samples were collected; animal are clinically improved. Proper rodent control measures were taken up in the farm to avoid spread of further infection. As the vaccination for leptospirosis is not fully effective, it must be used in combination with other control methods such as limiting exposure to stray dogs and wildlife, control of rodents, and elimination access to potentially contaminated food and water supplies.

Conclusion

Five serovars observed among buffaloes in the present study as well as in earlier studies are consistently prevalent among buffaloes in Tamil Nadu. Finally, further investigation on the effect of leptospira virulence on the reproductive performance of buffaloes and elucidation of the role of this livestock as either accidental hosts or carrier animals are needed to determine future actions to prevent leptospirosis from causing risks to public health and economic losses to the buffalo farming industry in Thanjavur Region of Tamilnadu.

Conflict of Interest

There is no conflict of interest

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